


Welcome to Your Life

by MsThunderFrost



Category: Undertale (Video Game)
Genre: Alternate Universe - Humantale (Undertale), Body Dysphoria, Chronically Ill Sans (Undertale), Engagement, Established Relationship, F/M, Female Reader, Human Papyrus (Undertale), Human Sans (Undertale), Mute Frisk (Undertale), Nonbinary Frisk (Undertale), Pregnancy, Pregnant Reader, Reader Is Not Chara (Undertale), Reader Is Not Frisk (Undertale), Sick Sans (Undertale), Teen Pregnancy, Trans Mettaton (Undertale), Unplanned Pregnancy
Language: English
Status: In-Progress
Published: 2020-07-14
Updated: 2020-07-19
Packaged: 2021-03-05 00:54:45
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 3,950
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25255750
Author URL: https://archiveofourown.org/users/MsThunderFrost/pseuds/MsThunderFrost
Summary: Sans didn't like to make promises. But, once upon a time, a perfect stranger had shown him a kindness that he didn't deserve and helped him to maintain custody of his little brother following their parents' deaths. He'd always wanted to repay the tremendous debt that he owed her... He just didn't know how.Until one day, when she asked that he look after her twelve-year-old child, Frisk, in the event anything happen to her.***Human!Sans and F!Reader adopt Frisk, who has become mute following the death of their mother, Toriel. Days after the paperwork is complete, the Reader discovers that she's pregnant, and must decide if she wishes to deliver the news to Sans, and how....and it seems that you're not the only one with an unexpected bun in the oven.
Relationships: Alphys/Undyne (Undertale), Frisk & Sans (Undertale), Frisk & Toriel (Undertale), Mettaton/Papyrus (Undertale), Sans (Undertale)/Reader
Comments: 4
Kudos: 45





	1. A Late Night Confession

It starts as a tickle in the back of his throat. 

He’s felt... _off_ for the last several days. A little too warm. A little more tired than usual. He hasn’t wanted to admit that it could be something, ‘cause he is still recovering from his latest bout of pneumonia and he isn’t keen on spending the next week and a half in the hospital recovering from an opportunistic infection. 

He knows that he should say something. You’ll be... _upset_ if you have to see him in another sterile room, attached to dozens of tubes and wires of various sizes that work to pump him full of medicine that’ll numb the pain wracking his body, unable to breathe without an obnoxiously loud machine forcing his shit lungs to expand. He understands. Well... not exactly. It’s difficult for him to understand, because it certainly doesn’t feel any better to wake-up in the middle of the night, drowning despite there not being a drop of water in sight. To _feel_ fluid and mucus pool in his lungs until every breath rattles and burns, until he cannot breathe at all.

It’s fucking terrifying－living with it, watching it... He’s been sick for twenty-five years. He doesn’t want to suffer anymore. But he doesn’t want you to suffer either, so he tries not to make a mountain out of a molehill. A little tickle could very well be nothing, especially considering he still has some gunk sitting at the bottom of his lungs. Or it could be something major. He shifts a bit, sliding his arm out from underneath you to thunk himself on the chest a couple of times. He starts coughing, and it sounds like someone trying to start a ten-year-old lawnmower. Little flecks of dark red blood splatter across the sleeve of his sleep shirt－

“Mmm,” a handle settles on Sans’ shoulder. It takes him awhile to get his coughing under control... so long that it’s actually a little disconcerting. “Shh... try to take a deep breath. I know it hurts, but it’ll pass in just a second.”

You thunk his back a couple times, and the fit passes in less than a minute. It feels like a small sliver of eternity. “Heh... t-thanks for that, kid. That was a bad one.”

Your eyes flicker down to the flecks of blood on his shirt. “Um... how about I make you some tea? I, uh... I know that you don’t really _like_ tea, but some slippery elm might help your throat...” 

Sans notices where you’re staring, and wastes no time rolling back his sleeve to hide the stains. It’s three in the morning. You should be worried about _sleeping_ , not making him tea that he doesn’t even want to drink. He will, of course, if only ‘cause you made it for him, but... “Don’t need it. Besides, you should be sleepin’.”

“It’s kinda hard to sleep with you over there, sounding like you’re dying.” You whisper. 

“It’s just a little tickle. Nothin’ to get your pretty little panties in a twist over.” He says. When you continue to stare at him in abject concern, he sighs, “Y’know what’d really help me out, though? A nice, big glass of ice water. And maybe a couple a Tylenol, too.”

You nod. It’s a slow process, detangling yourself from the stack of blankets atop your shared bed, but you’re not about to let something as inconsequential as _blankets_ stop you from helping your fiance in his hour of need. You’ve never been so thankful that your house is all one floor－the kitchen is a quick trip down the hall and to the right. You take one of the shatter-proof glasses from the cabinet next to the sink and activate the ice maker. It occurs to you, as you move to fill the glass with water, that you ought to get him another glass with just enough water to rinse the taste of blood out of his mouth...

Your fiance, Sans, had been born with a compromised immune system. He was always sick with something or other, and despite scenes like that which occurred in the bedroom being (unfortunately) relatively normal, you didn’t think you’d ever get used to the sight of the man you loved more than life itself coughing up mouthfuls of blood. It’s not... a _common_ occurrence, him spitting up blood, but it happens often enough that one would _think_ you’d be desensitized to it by now. But no. It still fills you with fear, makes you wonder if this’ll be the time he winds up in the hospital with something so serious he wouldn’t be coming back home. 

“Ya okay, dollface?” You jump. You hadn’t heard Sans leave the bedroom, so you certainly hadn’t been prepared for him to wrap his arms around your waist and burrow his face into the crook of your neck. “‘Thought that I heard somethin’ fall.”

You realize, then, that the glass had fallen out of your hand. If it weren’t for the shatter-proof glass, you’d be standing in a sea of broken glass. “O-Oh, I didn’t－,” You move, unconsciously, to start cleaning up the mess. Or, at least, you _try_. Sans’ grip on your waist keeps you still. 

“Leave it.” He says, “I don’t really need it. I’m just glad I didn’t ask ya to make me tea. Coulda burned yourself real bad.” He draws you in to his chest, his skin radiating an unnatural heat through the thin material of his sleep shirt.

“You have a fever.” You inhale shakily, wrapping your arms around his waist and clinging to him for all you’re worth.

He nods, “Yeah. ‘s probably not too high, though.” He hums softly, running his fingers through your hair. 

“Y-You should be laying down. Or... Or _resting_ , at least. It’s too early for anyone to be awake－,”

“Exactly,” Sans fixes you with a lazy smile. “It’s too early for _anyone_ to be awake right now. That includes you, princess.” He tucks a strand of hair behind your ear, “But lemme fill ya in on a lil’ secret. I ain’t goin’ back to bed without ya.”

You roll your eyes, “You’re a stubborn ass.”

“An’ that’s why ya love me.” He presses a kiss to the crown of your head, “But, uh... if you’re gonna be awake for a lil’ while, think ya could come and sit with me for a lil’ while? There’s somethin’ I wanna talk to ya about.”

“...at three in the morning?” Nevertheless, you allow your fiance to steer you toward the couch. If you can’t talk him back into bed, resting on the couch seems to be your best alternative. 

It’s not often that Sans wants to have a deep, heart-to-heart chat with you. That’s not to say that he’s _insincere_ . He just doesn’t like to make things too... _heavy_ between you. The lackluster state of his health robs you of enough sleep, he doesn’t want to put anything else on your plate. He wants you to be able to focus on things that’re fun (and stressful, in their own way), like planning the wedding you’d been putting off for... has it really been almost three and a half years since he proposed to you? Sans cringes, squeezing your hand ever-so-gently. At this point, it might just be easier to cut all the fancy-shmancy crap and elope...

That is, if you even still want to marry him after he tells you about... _them_ . He doesn’t know why he’s put it off for so long (okay, he absolutely _does_ , and it has nothing to do with being hospitalized for the better part of last month). ‘Cause this is the sort of thing he _probably_ should’ve talked you about－and, to be fair, he can’t remember why he’d chosen not too, at the time－ _before_ agreeing to it. But... you know...

He doesn’t like making promises. It’d taken him an _extremely_ long time to come around to the idea of promising himself to you forever, and he loved you more than anything. Except, perhaps, his baby brother. The ring tjust made it all so much more... _permanent_ . But he’s not meant to be contemplating the meaning of forever right now. He’s supposed to be taking your mind off of his shit lungs by confiding in you about his... err... _questionable_ life choices. 

“I, uh... I need ya to keep an open mind about this, alright?” You find yourself nodding. You’re too tired to question him... at least, not yet. Instead, you rest your head against his chest and listen to the slight rattle of his breath. “About five or six years back, I met this lady. Now, don’t be lookin’ at me like that, dollface. This ain’t that kinda story.”

“Sorry, sorry.” You fiddle with his sleeve, offering him an apologetic smile. “It’s just... I think the only woman I’ve ever heard you talk about is Undyne. And that’s usually just to bitch about how she’s riding your ass at work.”

Sans shrugs－that’s likely true. He knows a lot of people, but he doesn’t think of himself as having a lot of friends. The only people that he’s genuinely close to live under his roof. “Yeah. I suppose that makes sense.”

“Anyway... I didn’t mean to interrupt you. I want to hear what you have to say.” You say, cuddling up to his chest.

Coming his fingers through your hair, he continues, “‘s okay.” And then, “She’s the one that helped me get my job at the University. Y’know that nobody was lookin’ to hire a bonehead like me. I didn’t finish high school－,”

You frown, “That wasn’t your fault and you know it.” 

He gives you a little smile, “Yeah, well... That’s a bit heavy to be puttin’ on a resume, y’know? Anywho... Most people aren’t lookin’ to hire a high school dropout with no work experience to speak of. And if I didn’t find a way to pay the bills, I was gonna lose custody of Pap. I was gettin’ real desperate by the time I met Toriel.’

“She wasn’t like the other interviewers. Sure, she asked the same ol’ crap, like ‘why do you want to work for the University’... but she asked me about Pap. How he was doin’ in school. If there was someone at home that’d be able to look after ‘im while I worked the night shift. I, uh... got so caught up in our conversation, I didn’t even realize she’d basically given me the job ‘til she asked when I could start.’

“She used to bake birthday cakes for Pap, ‘n get him presents and shit. He calls her Auntie Torie... It’s real sweet.” His grip on you tightens almost imperceptibly. “She, uh... She asked me, one day, if I would look after her brat, in case anythin’ ever happened to her. And I... I _really_ don’t like makin’ promises, but... If she hadn’t a given me a chance, the state woulda taken Pap away. A-And I－,”

Twisting around in his arms, you reach up to drag your fingers through sweat-slick white hair. “Papyrus isn’t going anywhere. Except _maybe_ to college.” And then, “You need to take a couple deep breaths for me. You’re gonna have a fit.”

“I’m okay.” He says, doing the exact opposite of what you’d said. “I... I need to get this off my chest.” His mouth feels like he’s swallowed chalk. He’s regretting letting you leave that glass of water on the floor. “Toriel... passed away, the last time that I was in the hospital.”

“Sans?”

“I, uh... I’m now the legal guardian of a twelve-year-old kid.” He says, his voice clearly straining. “...Surprise?”


	2. A Secret Trip to the Store

“I...  _ What _ ?” Because there’s absolutely  _ no way _ that you’d heard him correctly. A child. A twelve-year-old child. 

“Well, I hafta say, I was expectin’ a bit more of a reaction.” He cracks a little smile, smoothing his hand along the curve of your spine. “I know that I shoulda said somethin’ sooner. But, well... I was sorta hopin’ that nothin’ would ever come of it, y’know? Guess I should know by now that everybody dies, huh?”

“I just... I don’t know what to say.” This... This is  _ big _ . A child. You and Sans had never really  _ talked _ about having kids, seeing as raising Papyrus was already a task and a half. You loved Papyrus to death, but  _ fuck _ if it wasn’t absolutely exhausting trying to keep up with that big, beautiful brain of his. 

“I, uh... think I’m gonna count my blessings that you’re not screamin’ my head off right now.” You wouldn’t scream at him. You’re... not entirely certain what you  _ would _ do, but you know that you wouldn’t  _ scream _ at him, at least. “You don’t hafta decide how ya feel about it right this second. I know that it’s... it’s a lot to take in all at once. But I...” he slides his tongue over his chapped bottom lip. “They’ll be here on Friday.”

“F-Friday?” That’s... less than two days away. You find yourself in such a state of shock, you cannot even muster the energy needed to be upset over the lack of notice. 

He winces, “Yeah, it’s... just a lil’ last minute. But y’know what they say－better late than never.”

You frown, “I’m pretty sure that’s, like... if you forget someone’s  _ birthday _ . Not, ‘oh, by the way, I－ _ we _ －adopted this kid that you’ve never met... no, that you’ve never even  _ heard _ of, until right this minute!”

A head of disheveled, white blond hair appears down the hallway, heralded by the soft  _ creak _ of a bedroom door opening. “I-Is everything alright? I, the great Papyrus, thought that I heard yelling...” 

You flinch. You don’t need to look up to know that your fiance is shooting his brother a sheepish, apologetic smile. “Nobody’s yellin’, Pap. We were just havin’ a lil’ talk, and things got...  _ spirited _ .” 

“Oh.” And Papyrus, bless his heart, takes this at face value. 

He doesn’t head back to bed, however. It would seem that nobody’s headed back to bed anytime soon. Your fiance’s baby brother shuffles into the living room and wiggles his way in-between your bodies. Sans rolls his eyes, and for a minute you wonder whether or not he’s going to say anything. He has to have mentioned all of this to Papyrus, right? You are, admittedly, uncertain as to how much the teen will understand. The poor cinnamon roll still thinks that Sans actually took his old, sickly golden retriever to a farm up north, where it’d be able to bask in the sun’s warm rays and run around in lush, verdant green fields... You’d wanted to tell him the truth, but... according to Sans, Papyrus didn’t handle death well, and so you’d held your tongue, for his sake.

But if what Sans’d said about Toriel was true, then she’d been close to Papyrus. Close enough to make him butterscotch-cinnamon birthday cakes and buy him action figures for his birthday. You remember how proud Papyrus had looked when he showed you his collection. Papyrus hald told you absolutely  _ anything _ and  _ everything _ that you could ever want to know about every last one of them－his enthusiasm was so heartwarmingly sweet! But honestly... you expected nothing less from a person who faced even the most mundane of tasks with a great big smile and a positive attitude. Papyrus is honestly too pure for this world. 

And that’s why... he deserves to know. 

Also, just ‘cause, you know, he deserves to know that he’s getting a new... sibling? Nibling? You aren’t exactly sure what the relationship between Sans and this new child will look like. You’re confident that he’ll tell them to refer to him in whatever way makes them the most comfortable, whilst secretly hoping that they steer clear of any of the variations of ‘dad’. He has... understandably  _ mixed _ feelings about that word. But still... considering that this kid is just half a year shy of being exactly  _ half _ of your fiance’s age, you’re fairly certain that they’ll see him as less of a ‘father-figure’ and more of a ‘big brother’. Which would, by default, make Papyrus their big brother, too.

But... what did that make  _ you _ ?

You didn’t really have a chance to consider it, as you realize then that both Sans and Papyrus are staring at you expectantly. You have a feeling that you missed something rather...  _ important,  _ if the pointed look that Sans is giving you is any indication. Sans presses a kiss to the crown of Papyrus’ head, before making a mess of his already horribly disheveled bed-head. Papyrus huffs underneath his breath and swats at his brother halfheartedly, puffing out his cheeks in an adorable display of childish innocence as Sans stands and yawns, announcing that he’s heading back to bed. He coughs a bit, but it sounds more like he’s trying to clear his throat and less like he’s drowning in a sea of assorted bodily fluids, so you try not to worry too much. It doesn’t exactly  _ work _ , but...

As soon as Sans is out of earshot, Papyrus turns to you with a nervous look on his face. “Can we... um...  _ talk _ ?”

You’re not sure that you can handle anymore  _ talks _ today. And you know that it’s serious－it’s not often that Papyrus comes to you with something he cannot talk to his brother about, after all. “Sure. What’s up?”

“I, um...” a dark blush stains Papyrus’ pale cheeks as he blurts out, “I was wondering if you’d be willing to take me to the... to the store. I n-need to buy some...  _ things _ .”

You raise a brow, “Um... sure. I don’t see why not. Why don’t we head over to Wal-Mart after you’re done with school?” Papyrus nods, looking visibly relieved, and you cannot help but feel the need to press the issue, just a bit. “Not that I’m not  _ thrilled _ at the chance to take a mid-week trip to Wal-Mart, but, uh... Is there any particular reason Sans can’t know what it is you’re buying?”

Papyrus shifts a little, lowering his eyes to study a particularly fascinating stain on the couch. “I’d... prefer it if Sans doesn’t know. T-This is already really,  _ really _ weird but... you won’t make it awkward, right?” He looks at you hopefully. You nod, despite having absolutely no idea what it is that you’re agreeing to.

“No worries, little buddy. This here is a judgment free zone.” You say.

“I need to buy condoms.”

You proceed to choke on the air. W- _ What _ ? You suppose that it shouldn’t come as so much of a surprise, considering that Papyrus and Mettaton have been together, in one way or another, since long before you’d made things official with Sans. And somewhere, beneath the shock at hearing the precious cinnamon roll ask you to take him to Wal-Mart to buy  _ condoms _ , of all things, you’re proud that he at least has the foresight to use protection. But that doesn’t change the fact that you feel like this is the sort of thing  _ Sans _ should be doing. Not that you wouldn’t be able to advise him, but... You take a deep breath, rising off of the couch to go and clean the mess that you’d made in the kitchen. You  _ really _ need to be doing something with your hands right now.

Papyrus follows you into the kitchen like a lost puppy, rambling on about how it’s less about whether or not Sans’ll care that he’s having sex and more about the fact that he’ll be pissed he’s having sex with  _ Mettaton. _ Once upon a time, Sans’d tried to explain to you exactly what it was that he didn’t like about Mettaton－essentially, it boiled down to the fact that, in Sans’ eyes, nobody would ever be good enough for Papyrus. Sans hadn’t said anything to either of them directly, of course. That wasn’t his way. But he’d, er...  _ chaperoned _ enough dates that he’d made his opinion of them rather clear. 

“I feel bad. L-Like I’m stuck between a rock and a hard place. I love Sans more than anything, and it tears me up that he can’t see what a great person Mettaton is! And I... I know that Metta tries to act like it doesn’t bother him, but...” Papyrus fidgets, “I just... don’t want to upset anyone.”

“Have you... talked to Sans about any of this?” You have to ask, even though you’re confident you already know the answer. There were many things that Papyrus would nag his elder brother about－

－his love-life did not rank highly on that list... if it made the list at all. 

The flustered look on his face is answer enough. You tear off a wad of paper towels and use them to sop up the mess on the floor. “Y-You won’t tell Sans, right? ‘C-Cause, once he gets over the whole sleeping with Mettaton thing...  _ if _ he gets over the whole sleeping with Mettaton thing,” he repeats underneath his breath, “he’ll want to, y’know...”

“You... might have to help me out a bit here, Pap. It’s been a rough morning, and it’s not even four yet.” Papyrus, if possible, turns an even brighter shade of red. 

“H-He’ll try to give me...  _ advice _ .” He says. 

“Ahh... hmm,” your mouth snaps closed with an audible  _ clack _ , “Yeah... I can see how that could be a bit...  _ awkward _ .”

“Yeah, I... I love him, truly, but I... the great Papyrus doesn’t need a sex-ed lesson from his big brother.” Doing his best to keep himself busy, if only to have an excuse to not have to look you in the eye, he starts rinsing out the glass that you’d dropped earlier. “...It’s bad enough that I can hear the two of you through the wall.” He mumbles.

“You  _ what _ ?!” God... if that’s  _ true _ , then Sans is never touching you again. Never. 

“Nothing!” He chirps, before proceeding to drop the glass,  _ again _ .

You’re about ready to just crawl into a hole and die. A small part of you is still holding out for the fact that you’re still in bed, having an extremely vivid fever-dream. This is your body’s way of saying that you’ve been under too much stress lately, that you need to take some time for yourself to relax and unwind and... But Papyrus is staring at you like you just explained to him where babies come from in extraordinarily vivid detail and you manage to stammer out a quick ‘I’ll see you in the morning’ before  _ bolting _ back to the bedroom like you’re being chased by the hounds of hell. You leave the paper towels on the floor and everything (though, knowing Papyrus, if he’s not too flustered from your...  _ conversation _ , he’ll take care of the mess). 

Sans barely has the wherewithal to move his arm out of the way before you catapult face-first onto the bed and hide your face in the mass of pillows with a groan. He grumbles something about you making too much noise, before wrapping an arm around your waist and tugging you into his chest. You bury your face in the crook of his neck and try your damndest to ignore the slight whistle when he breathes. 

In the morning (or, rather,  _ later _ that morning), when he inevitably asks you what Pap wanted, you tell him that you’re taking him to the store to buy ingredients for his latest experimental pasta dish. If he suspects anything, he doesn’t say. 

You hate that your first thought is that, even if he did, it’s not like he has a leg to stand on, considering the magnitude of the secret  _ he’s _ been keeping...


End file.
